ExxonMobil pleaded guilty in federal court to killing 85 birds that had come into contact with crude oil or other pollutants in uncovered tanks or waste-water facilities on its properties. The birds were protected by the Migratory Bird Treaty Act, which dates back to 1918. The company agreed to pay $600,000 in fines and fees.

ExxonMobil is hardly alone in running afoul of this law. Over the past two decades, federal officials have brought hundreds of similar cases against energy companies. In July, for example, the Oregon-based electric utility PacifiCorp paid $1.4 million in fines and restitution for killing 232 eagles in Wyoming over the past two years. The birds were electrocuted by poorly-designed power lines.

Yet there is one group of energy producers that are not being prosecuted for killing birds: wind-power companies. And wind-powered turbines are killing a vast number of birds every year.

A July 2008 study of the wind farm at Altamont Pass, Calif., estimated that its turbines kill an average of 80 golden eagles per year. The study, funded by the Alameda County Community Development Agency, also estimated that about 10,000 birds—nearly all protected by the migratory bird act—are being whacked every year at Altamont.

Altamont’s turbines, located about 30 miles east of Oakland, Calif., kill more than 100 times as many birds as Exxon’s tanks, and they do so every year. But the Altamont Pass wind farm does not face the same threat of prosecution, even though the bird kills at Altamont have been repeatedly documented by biologists since the mid-1990s.

The number of birds killed by wind turbines is highly variable. And biologists believe Altamont, which uses older turbine technology, may be the worst example. But that said, the carnage there likely represents only a fraction of the number of birds killed by windmills. Michael Fry of the American Bird Conservancy estimates that U.S. wind turbines kill between 75,000 and 275,000 birds per year. Yet the Justice Department is not bringing cases against wind companies.

“Somebody has given the wind industry a get-out-of-jail-free card,” Mr. Fry told me. “If there were even one prosecution,” he added, the wind industry would be forced to take the issue seriously.

“The fix here is not easy or cheap,” Mr. Lee told me. He added that he doesn’t expect to see any prosecutions of the politically correct wind industry.

This is a double standard that more people—and not just bird lovers—should be paying attention to. In protecting America’s wildlife, federal law-enforcement officials are turning a blind eye to the harm done by “green” energy.

"Anyone who goes around and says that carbon dioxide is responsible for most of the warming of the 20th century hasn't look at the basic numbers."Patrick Michaels - Ph.D. Ecological Climatology, Professor of Environmental Sciences, U. of Virginia

“We have 25 or so years invested in the work. Why should I make the data available to you, when your aim is to try and find something wrong with it.”Phil Jones, Professor in the School of Environmental Sciences at University of East Anglia, to Steve McIntyre